Electropotential mapping

Abstract

A method for forming an electropotential map, including: measuring locations of points on a surface of a body organ, and measuring electrical potentials of a subset of the points. The method further includes assigning respective resistances to line segments joining the points so as to define a resistor mesh, and generating an electropotential map of the surface by applying an harmonic function to the resistor mesh responsive to the measured electrical potentials.

We claim: 
     
       1. A method for forming an electropotential map, comprising:
 measuring locations of points on a surface of a body organ; 
 measuring electrical potentials of a subset of the points; 
 assigning respective resistances to line segments joining the points so as to define a resistor mesh; and 
 generating an electropotential map of the surface by applying an harmonic function to the resistor mesh responsive to the measured electrical potentials. 
 
     
     
       2. The method according to  claim 1 , wherein the body organ comprises a heart of a human subject. 
     
     
       3. The method according to  claim 2 , wherein the electropotential map comprises a map of respective potentials associated with local activation times of the heart. 
     
     
       4. The method according to  claim 1 , wherein measuring the locations comprises inserting a probe into the body organ, and tracking a distal end of the probe in contact with the surface. 
     
     
       5. The method according to  claim 4 , wherein the distal end comprises tracking coils located therein, and wherein tracking the distal end comprises receiving and analyzing signals from the tracking coils. 
     
     
       6. The method according to  claim 4 , wherein the distal end comprises an electrode attached thereto, and wherein measuring the electrical potentials comprises measuring the electrical potentials using the electrode. 
     
     
       7. The method according to  claim 6 , wherein tracking the distal end comprises measuring an impedance between the electrode and electrodes attached to skin of a human subject having the body organ. 
     
     
       8. The method according to  claim 1 , and comprising forming the line segments as a triangular mesh. 
     
     
       9. The method according to  claim 1 , wherein the line segments have respective lengths, and wherein assigning the respective resistances comprises assigning the respective resistances to be directly proportional to the respective lengths. 
     
     
       10. The method according to  claim 1 , wherein applying the harmonic function comprises applying a Kirchhoffs circuit law to the resistor mesh. 
     
     
       11. The method according to  claim 10 , wherein the Kirchhoff s circuit law comprises Kirchhoff s current law. 
     
     
       12. The method according to  claim 10 , wherein generating the electropotential map comprises using the Kirchhoff s circuit law to determine electrical potentials of the points on the surface not in the subset. 
     
     
       13. Apparatus for forming an electropotential map, comprising:
 (a) a probe configured to:
 (i) measure locations of points on a surface of a body organ, and 
 (ii) measure electrical potentials of a subset of the points; and 
 
 (b) a processor configured to:
 (i) assign respective resistances to line segments joining the points so as to define a resistor mesh, 
 (ii) apply a harmonic function to the resistor mesh responsive to the measured electrical potentials; and 
 (iii) generate an electropotential map of the surface of the body organ using the resistor mesh and the harmonic function. 
 
 
     
     
       14. The apparatus according to  claim 13 , wherein the body organ comprises a heart of a human subject. 
     
     
       15. The apparatus according to  claim 14 , wherein the electropotential map comprises a map of respective potentials associated with local activation times of the heart. 
     
     
       16. The apparatus according to  claim 13 , wherein the processor is configured to track a distal end of the probe inserted into the body organ and in contact with the surface. 
     
     
       17. The apparatus according to  claim 16 , wherein the distal end comprises tracking coils located therein, and wherein tracking the distal end comprises receiving and analyzing signals from the tracking coils. 
     
     
       18. The apparatus according to  claim 16 , wherein the distal end comprises an electrode attached thereto, and wherein measuring the electrical potentials comprises measuring the electrical potentials using the electrode. 
     
     
       19. The apparatus according to  claim 18 , wherein tracking the distal end comprises measuring an impedance between the electrode and electrodes attached to skin of a human subject having the body organ. 
     
     
       20. The apparatus according to  claim 13 , and comprising forming the line segments as a triangular mesh. 
     
     
       21. The apparatus according to  claim 13 , wherein the line segments have respective lengths, and wherein assigning the respective resistances comprises assigning the respective resistances to be directly proportional to the respective lengths. 
     
     
       22. The apparatus according to  claim 13 , wherein applying the harmonic function comprises applying a Kirchhoff s circuit law to the resistor mesh. 
     
     
       23. The apparatus according to  claim 22 , wherein the Kirchhoff s circuit law comprises Kirchhoff s current law. 
     
     
       24. The apparatus according to  claim 22 , wherein generating the electropotential map comprises using the Kirchhoff s circuit law to determine electrical potentials of the points on the surface not in the subset.